1/* SPDX-License-Identifier: GPL-2.0 */ 2/* 3 * __get_user functions. 4 * 5 * (C) Copyright 1998 Linus Torvalds 6 * (C) Copyright 2005 Andi Kleen 7 * (C) Copyright 2008 Glauber Costa 8 * 9 * These functions have a non-standard call interface 10 * to make them more efficient, especially as they 11 * return an error value in addition to the "real" 12 * return value. 13 */ 14 15/* 16 * __get_user_X 17 * 18 * Inputs: %[r|e]ax contains the address. 19 * 20 * Outputs: %[r|e]ax is error code (0 or -EFAULT) 21 * %[r|e]dx contains zero-extended value 22 * %ecx contains the high half for 32-bit __get_user_8 23 * 24 * 25 * These functions should not modify any other registers, 26 * as they get called from within inline assembly. 27 */ 28 29#include <linux/export.h> 30#include <linux/linkage.h> 31#include <asm/page_types.h> 32#include <asm/errno.h> 33#include <asm/asm-offsets.h> 34#include <asm/thread_info.h> 35#include <asm/asm.h> 36#include <asm/smap.h> 37 38#define ASM_BARRIER_NOSPEC ALTERNATIVE "", "lfence", X86_FEATURE_LFENCE_RDTSC 39 40.macro check_range size:req 41.if IS_ENABLED(CONFIG_X86_64) 42 movq $0x0123456789abcdef,%rdx 43 1: 44 .pushsection runtime_ptr_USER_PTR_MAX,"a" 45 .long 1b - 8 - . 46 .popsection 47 cmp %rax, %rdx 48 sbb %rdx, %rdx 49 or %rdx, %rax 50.else 51 cmp $TASK_SIZE_MAX-\size+1, %eax 52 jae .Lbad_get_user 53 sbb %edx, %edx /* array_index_mask_nospec() */ 54 and %edx, %eax 55.endif 56.endm 57 58.macro UACCESS op src dst 591: \op \src,\dst 60 _ASM_EXTABLE_UA(1b, __get_user_handle_exception) 61.endm 62 63 64 .text 65SYM_FUNC_START(__get_user_1) 66 check_range size=1 67 ASM_STAC 68 UACCESS movzbl (%_ASM_AX),%edx 69 xor %eax,%eax 70 ASM_CLAC 71 RET 72SYM_FUNC_END(__get_user_1) 73EXPORT_SYMBOL(__get_user_1) 74 75SYM_FUNC_START(__get_user_2) 76 check_range size=2 77 ASM_STAC 78 UACCESS movzwl (%_ASM_AX),%edx 79 xor %eax,%eax 80 ASM_CLAC 81 RET 82SYM_FUNC_END(__get_user_2) 83EXPORT_SYMBOL(__get_user_2) 84 85SYM_FUNC_START(__get_user_4) 86 check_range size=4 87 ASM_STAC 88 UACCESS movl (%_ASM_AX),%edx 89 xor %eax,%eax 90 ASM_CLAC 91 RET 92SYM_FUNC_END(__get_user_4) 93EXPORT_SYMBOL(__get_user_4) 94 95SYM_FUNC_START(__get_user_8) 96#ifndef CONFIG_X86_64 97 xor %ecx,%ecx 98#endif 99 check_range size=8 100 ASM_STAC 101#ifdef CONFIG_X86_64 102 UACCESS movq (%_ASM_AX),%rdx 103#else 104 UACCESS movl (%_ASM_AX),%edx 105 UACCESS movl 4(%_ASM_AX),%ecx 106#endif 107 xor %eax,%eax 108 ASM_CLAC 109 RET 110SYM_FUNC_END(__get_user_8) 111EXPORT_SYMBOL(__get_user_8) 112 113/* .. and the same for __get_user, just without the range checks */ 114SYM_FUNC_START(__get_user_nocheck_1) 115 ASM_STAC 116 ASM_BARRIER_NOSPEC 117 UACCESS movzbl (%_ASM_AX),%edx 118 xor %eax,%eax 119 ASM_CLAC 120 RET 121SYM_FUNC_END(__get_user_nocheck_1) 122EXPORT_SYMBOL(__get_user_nocheck_1) 123 124SYM_FUNC_START(__get_user_nocheck_2) 125 ASM_STAC 126 ASM_BARRIER_NOSPEC 127 UACCESS movzwl (%_ASM_AX),%edx 128 xor %eax,%eax 129 ASM_CLAC 130 RET 131SYM_FUNC_END(__get_user_nocheck_2) 132EXPORT_SYMBOL(__get_user_nocheck_2) 133 134SYM_FUNC_START(__get_user_nocheck_4) 135 ASM_STAC 136 ASM_BARRIER_NOSPEC 137 UACCESS movl (%_ASM_AX),%edx 138 xor %eax,%eax 139 ASM_CLAC 140 RET 141SYM_FUNC_END(__get_user_nocheck_4) 142EXPORT_SYMBOL(__get_user_nocheck_4) 143 144SYM_FUNC_START(__get_user_nocheck_8) 145 ASM_STAC 146 ASM_BARRIER_NOSPEC 147#ifdef CONFIG_X86_64 148 UACCESS movq (%_ASM_AX),%rdx 149#else 150 xor %ecx,%ecx 151 UACCESS movl (%_ASM_AX),%edx 152 UACCESS movl 4(%_ASM_AX),%ecx 153#endif 154 xor %eax,%eax 155 ASM_CLAC 156 RET 157SYM_FUNC_END(__get_user_nocheck_8) 158EXPORT_SYMBOL(__get_user_nocheck_8) 159 160 161SYM_CODE_START_LOCAL(__get_user_handle_exception) 162 ASM_CLAC 163.Lbad_get_user: 164 xor %edx,%edx 165 mov $(-EFAULT),%_ASM_AX 166 RET 167SYM_CODE_END(__get_user_handle_exception) 168